New Risk Factors Seen on Hypertension

By LAWRENCE K. ALTMAN

Published: December 23, 1993

People with slightly elevated systolic blood pressure, the higher of the two blood pressure readings, are at increased risk of developing full-fledged hypertension and heart disease compared with those with normal blood pressure, a new study has found.

People with the condition, borderline systolic hypertension, have generally not been classified as having high blood pressure because the slight elevations were not known to be potentially harmful.

The findings concern systolic blood pressures from 140 to 159 millimeters of mercury and a diastolic reading (the lower number) below 90. The findings come from the landmark Framingham Heart Study, which has been following initially healthy adults in Massachusetts for more than 40 years to determine which factors most strongly influence a person's risk of developing heart disease. The findings are being published today in The New England Journal of Medicine. Least Thoroughly Studied

The authors said such borderline hypertension was the most common form of untreated high blood pressure among those over 60 years old and the least thoroughly studied type of high blood pressure.

Nomenclature for systolic readings varies among medical groups. The Framingham study used the World Health Organization's definition of borderline isolated systolic hypertension for readings from 140 to 159. (Isolated means the hypertension definition is based on the systolic pressure independent of the diastolic reading.)

The federally sponsored National High Blood Pressure Education Program defines a systolic pressure from 140 to 160 and a diastolic of less than 90 as Stage 1 systolic hypertension.

The authors of the new Framingham study urged doctors to inform people if they have borderline systolic high blood pressure and to advise them to have it checked frequently.

But the authors said further research was needed to determine whether treatment with measures like diet, exercise and drugs would prevent heart ailments and extend the lives of people with borderline systolic hypertension. The reason is that studies have not been done to determine the benefits of such treatment among people with borderline systolic hypertension. Caution on Drug Therapy

Two independent experts underscored the need to tailor therapy to each patient and urged caution in first treating borderline systolic hypertension with drugs.

Dr. Marvin Moser of White Plains, a consultant to national high blood pressure programs, said it would be prudent to first try to reduce borderline systolic blood pressure by diet and weight loss. But, he added, it might be difficult to do so in many people.

Dr. Michael H. Alderman, an expert in high blood pressure who heads the department of preventive medicine at Albert Einstein Medical School in the Bronx, said further research on drugs to treat borderline systolic hypertension was needed because the adverse effects of standard anti-high blood pressure drugs might be greater than the benefits.

Dr. Alderman said the new study added "weight to the notion that at any level of blood pressure, you are better off if your blood pressure was lower."

The study also adds to what the authors said was "compelling evidence" that the systolic reading was at least as important as the diastolic reading as a contributor to heart disease.

For decades, doctors emphasized that the greatest risk of hypertension was from high readings of the diastolic pressure.

But in 1991, a federally financed study showed that treatment of definite systolic hypertension in elderly people substantially decreased the incidence of stroke, heart attacks and other heart disease. Such problems are long-term complications of untreated high blood pressure. Financed by Federal Agency

Authors of the Framingham study said it was not clear whether the risk of borderline systolic hypertension on the heart was indirect or direct by progression to definite hypertension. The authors were headed by Dr. Daniel Levy, and included Dr. Martin G. Larson and Dr. Alex Sagie. The study was financed by the National Heart, Lung and Blood Institute, a Federal agency in Bethesda, Md.

The study's findings were based on 2,767 of the original participants in the Framingham study. The participants, who ranged in age from 28 to 62 at entry, were monitored with check-ups every two years for up to 34 years. Fifty-nine percent of the participants were women.

After 34 years, 1,132 participants had died. A total of 1,010 had developed heart and circulatory disease and 228 had developed heart failure.

After 20 years of follow-up, 80 percent of those who early on had borderline systolic hypertension progressed to full-fledged high blood pressure, compared with 45 percent of the participants with normal blood pressures. Those with borderline systolic hypertension had a significantly greater risk of developing heart attacks, heart failure and strokes than those with normal blood pressure.

The risk of heart disease was also increased among those with borderline systolic hypertension who did not later develop full-fledged high blood pressure.